feat(plugin): expose stable sidebar entity data across hosts

Collections return interned references and preserve their arrays when membership and order stay unchanged. Entity selectors share one hook with identity defaults for full snapshots and shallow defaults for selections. The app caches host projections and shares underlying store and host subscriptions. Browser render counts exercise the real session store and plugin provider without memoized rows. Terminal hooks consume the collection source port; daemon-wide terminal discovery is the separate terminal phase.

packages/plugin/src/client/host.ts

@@ -1,6 +1,11 @@
 import type { PluginText } from "../text.js";
 import { PluginAttachmentSearchPayloadSchema } from "../attachments.js";
-export { PluginClientStateProvider, type PluginClientStateSource } from "./client-state.js";
+export {
+  PluginClientStateProvider,
+  usePaseoSelector,
+  type PluginClientStateSource,
+  type PluginClientSnapshot,
+} from "./client-state.js";
 export {
   usePluginRuntimeContextBridge,
   type PluginRuntimeContextBridge,
@@ -31,3 +36,5 @@ export {
   isPluginMessage,
 } from "./translations.js";
 export type { PluginLocaleSource } from "./translations.js";
+
+export { createEntityRefs } from "./refs.js";